The field of this invention is that of contactless travel keyboards for use in electronic business machines, data terminals and the like. The keyboards provide electrical control signals corresponding to the actuation of respective key switches on the keyboard.
Many conventional electronic equipments and devices use travel type keyboards in which substantial movement of a key is associated with the actuation of each key switch. That movement is considered desirable because it is believed to facilitate operator use of the keyboard and to provide more reliable input of data to the equipment. Such keyboards typically incorporate pairs of mating electrical contacts which are engaged and disengaged in response to key movement and, as will be understood, the designs of such keyboards usually represent conventional compromises between design factors such as cost, reliability and contact service life. Other keyboards of a contactless type, based on the use of capacitive switches or on the use of Hall effect devices or other magnetic means, have also been proposed for use in such electronic apparatus in attempting to achieve lower keyboard costs or improved keyboard reliability or the like. Usually however such contactless systems have tended to be more complex and have involved close matching of device component characteristics so that few of the objectives of improved cost or reliability have been achieved. With the growing interest in many new applications of data terminals for general consumer use, it would be desirable to provide a contactless type of travel keyboard characterized by improved low cost manufacture, by high reliability and by long service life.
It is an object of this invention to provide such a novel and improved contactless travel keyboard; to provide such a keyboard which incorporates inexpensive and easily manufactured components, which is easily assembled, and which is stable, rugged and reliable in use over a long service life; to provide such a keyboard which is reliable and cost effective for use in data terminals, computers, word-processing electronic equipment and the like in general consumer applications; to provide such a keyboard which is not subject to excessive wear; which is operable in hostile environments including high humidity, dust/dirt or beverage-spill conditions and the like, and which is energy efficient and operable at low cost; and to provide such a contactless keyboard which is substantially unaffected by extraneous electromagnetic fields, r.f. noise, or the proximity of other electrical equipment.